Method and apparatus for processing coded aperture radar (CAR) signals

Abstract

A radar system in which Coded Aperture Radar processing is performed on received radar signals reflected by one or more objects in a field of view which reflect a transmitted signal which covers a field of view with K sweeps and each sweep including Q frequency changes. For Type II CAR, the transmitted signal also includes N modulated codes per frequency step. The received radar signals are modulated by a plurality of binary modulators the results of which are applied to a mixer. The output of the mixer, for one acquisition results in a set of Q·K (for Type I CAR) or Q·K·N (for Type II CAR) complex data samples, is distributed among a number of digital channels, each corresponding to a desired beam direction. For each channel, the complex digital samples are multiplied, sample by sample, by a complex signal mask that is different for each channel.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 61 / 912,990, filed Dec. 6, 2013 and entitled “A Method and Apparatus for Processing Coded Aperture Radar Signals”. The disclosure of that U.S. Provisional Patent Application Ser. No. 61 / 912,990, is hereby incorporated herein by this reference.[0002]This application is related to U.S. patent application Ser. No. 13 / 490,607 filed Jun. 7, 2012 and entitled “Coded Aperture Beam Analysis Method and Apparatus”, the disclosure of which is hereby incorporated herein by reference.[0003]This application is also related to U.S. patent application Ser. No. 13 / 725,621, filed Dec. 21, 2012 and entitled “Coded Aperture Beam Analysis Method and Apparatus”, the disclosure of which is hereby incorporated herein by reference.[0004]This application is also related to U.S. patent application Ser. No. ______ filed on the same date as this application, Dec. 4, 201...

AI Technical Summary

Benefits of technology

The present invention is about a method for processing radar signals reflected from objects in a field of view of a radar transmitter. The method involves using binary phase shifters to modulate the reflected signals and produce modulated signals. These signals are then summed and down converted to base band. The resulting real and imaginary digital values are distributed into multiple channels, with each channel corresponding to a desired radar beam direction. A complex multiplication is performed using the real and imaginary digital values and the signal mask for each channel to produce a multiplication result that can be organized into a matrix with each column and row corresponding to a different sweep of the transmitted radar signal. The transformed data is then produced by performing a transformational function on the multiplication results. The transformed data matrix reflects the scattering strength of objects in the field of view at different ranges and velocities. Overall, this method allows for improved radar signal processing and detection of objects in the field of view.

Problems solved by technology

CAR is a new technology that has not yet been implemented in IC form, therefore is no known prior art for processing methods and hardware for CAR signals.

This technique is effective, but requires an often prohibitive amount of memory to store the reference signals, and significant computation to perform the correlations in a CPU (for example).

This is highly computationally intensive and introduces significant latency for large arrays due to the limited speed with which basic digital calculations (e.g., multiplications) may be made.

However, the fact that digital beamforming combines signals from all the elements creates highly complex combining networks that quickly become unfeasible as the array gets large and even more particularly so if the array is a two dimensional (2D) array.

Images